<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <title>Title</title>
    <style type="text/css">
        .main{
            display: flex;
            justify-content: space-between;/*对齐方式*/
            flex-direction:column;
        }
        .item{
            width: 200px;
            height: 200px;
            line-height: 200px;
            border-radius: 3px;
            background: #d3d3d3;
            color: #999;
            font-size: 50px;
            text-align: center;
        }
    </style>
</head>
<body>
<div class="main">
    <div class="item">1</div>
    <div class="item">2</div>
    <div class="item">3</div>
</div>
</body>
</html>